Conventionally, in a detergent used for clothing, a detergent builder (a detergent auxiliary) such as zeolite, carboxymethyl cellulose and polyethylene glycol has been formulated to improve washing effect of a detergent.
Also, recently, in addition to the above various detergent builders, a polymer is formulated in a detergent composition as a detergent builder.
For example, use of a water-soluble and water-dispersion type graft polymer having predetermined amount of a graft component and a hydrophobic residue, bound with the graft component via a polyglycol ether chain having predetermined chain length, as a detergent builder, is disclosed (see JP-A-59-62614).
In addition, a graft polymer composition, as a detergent particularly suitable to a liquid detergent, is disclosed as containing 2 or more kinds of graft polymers obtained by graft polymerization of monomer components containing an unsaturated carboxylic acid-based monomer, onto a main chain containing a polyether moiety, wherein number of carbon atoms of terminal structure units differ by equal to or more than 3, when the numbers of carbon atoms composing the structure units located at both terminals of each of main chains, between 2 kinds of graft polymers among the 2 or more kinds of graft polymers, are compared with, under predetermined condition (see JP-A-2002-332391).
It should be noted that, performances presently required to a detergent builder include not only performance to improve washing capability of a detergent, as a matter of course, but also performance to suppress/prevent deposition of a surfactant or soil re-deposition. Here, the deposition problem of a surfactant is more apparent in washing using water with relatively high hardness, because the deposition is generated by bonding of straight chain alkylbenzene sulfonic acid (or a salt) (LAS) such as dodecylbenzene sulfonic acid, that is an anionic surfactant, with calcium ions or magnesium ions present in water (see Louis Ho Tan Tai, “Formulating Detergent and Personal Care Products” AOCS Press, pp 53 to 54 (2000)).
However, any of the above graft polymers, when used as detergent builders, did not necessarily satisfy performance to suppress deposition of a surfactant (hereafter may be referred to as simply “deposition suppression capability”) and/or performance to suppress soil (in particular, hydrophobic soil such as clay) re-deposition (hereafter may referred to as simply “prevention capability of soil re-deposition”).
Note that, although not for an application of a detergent builder, a graft polymer having a structure similar to that of the above polymer is also known; for example, as a graft polymer used as a paper surface processing agent, a graft polymer obtained by graft polymerization of a polyether (A), a predetermined ethylene-type unsaturated monomer (B) and, if necessary, other monomers (C), in predetermined ratio, is known (see JP-A-58-109700). Further, as a graft polymer used as a dye or a fluorescent whitening agent, a graft polymer obtained by containing side chains derived from an ethylene-type unsaturated monomer, onto carbon atoms of polyalkylene glycol ether chains, where 2 terminal hydroxyl groups of polyalkylene glycol are esterified by a C8 to C26 fatty acid, is known (see JP-A-62-4712).